Sodium Doped Strontium Silicates as Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

The conventional solid oxide fuel cell electrolyte, yttria stabilized zirconia requires high operating temperature (800-1000 degrees C) to achieve sufficient oxide ion conductivity, which increases the cost and exacerbates the instability between the components. Therefore, there is considerable interest in developing alternative electrolytes (sigma > 10(-2) S/ cm) at intermediate temperature (IT, 500-700 degrees C). Hence, here we successfully synthesized IT operable electrolytes Sr1-xNaxSiO3-delta (x = 0.0, 0.45) by solid state reactions. From the XRD, it is evident that both samples can be indexed to monoclinic c2/c space group (15). NMR reveals a broad peak at similar to -87 ppm for Sr0.55Na0.45SiO3-delta indicating the presence of amorphous Na2Si2O5 phase. FE-SEM and WDS mapping shows the segregation of amorphous Na2Si2O5 along the grain boundaries. Sr0.55Na0.45SiO3-delta exhibits high conductivity in the measured temperature range, which makes it an electrolyte for IT-SOFCs.